Squirrels again

Andrew Lee said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

They're back, they're bad, and they're fuzzy!

Shoulda titled this thread "squirrels vs. forks!"

Mark

In article <[email hidden]>, Mark Janeba

Quoted message said:

Andrew Lee said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

They're back, they're bad, and they're fuzzy!

Shoulda titled this thread "squirrels vs. forks!"

Mark

Aha, another reason to avoid boutique wheelsets! Would the squirrel
have become lodged if the bike was rolling along on 3x 36 spoke hoops
(stress relieved and tensioned as per The Bicycle Wheel by Jobst
Brandt, of course)?

Take care, if the PETA zealots catch wind of this then a phalanx of
protesters decrying the inhumanity of paired spoke Bontragers will
surely picket your LBS!

What a fool I've been! All these years, stuffing my face with Vitamin M
in the vain hope that Pammy Anderson, picketing the local McDonald's,
would throw herself at me and possess herself of my Quarter Pounder. If
I'd only known a Bontrager wheelset would do the trick.

"Andrew Lee" <whatsupandrewathotmaildotcom> wrote in message
news:[email hidden]...

Quoted message said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

In the earlier thread some opined that a soft squirrel was not capable of
causing this type of accident. I still think that there is enough substance
to a squirrel to stop the front wheel. These photos look authentic enough
and I would love to learn the details.

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded, there must be
a vertical force in excess of the combined rider and bike weight. I can't
tell if it is carbon or not. If it is carbon, carbon forks often take 800
lbs or so to break when loaded at the dropout. If the force is applied to
the tire contact patch, the moment arm is roughly doubled and it requires a
force on the order of 400 lbs to break the fork (some forks may be stronger
or weaker). John Forester proposes how this might happen here:
http://www.johnforester.com/Articles/BicycleEng/forkbend.htm
I have looked at this type of failure before and tried to figure out the
dynamics. I think it can occur but is very rare. I am not sure but a ductile
(e.g steel) fork may perform better in this scenario than a more brittle
(e.g carbon fiber) fork.

Dan said:

"Andrew Lee" <whatsupandrewathotmaildotcom> wrote in message
news:[email hidden]...

Quoted message said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his
friend on Mark's bike in last month's thread (except the bike is not
a Habanero). I wonder what that fork is aluminum or carbon?

In the earlier thread some opined that a soft squirrel was not
capable of causing this type of accident. I still think that there is
enough substance to a squirrel to stop the front wheel. These photos
look authentic enough and I would love to learn the details.

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded,
there must be a vertical force in excess of the combined rider and
bike weight. I can't tell if it is carbon or not. If it is carbon,
carbon forks often take 800 lbs or so to break when loaded at the
dropout. If the force is applied to the tire contact patch, the
moment arm is roughly doubled and it requires a force on the order of
400 lbs to break the fork (some forks may be stronger or weaker).
John Forester proposes how this might happen here:
http://www.johnforester.com/Articles/BicycleEng/forkbend.htm I have looked
at this type of failure before and tried to figure out
the dynamics. I think it can occur but is very rare. I am not sure
but a ductile (e.g steel) fork may perform better in this scenario
than a more brittle (e.g carbon fiber) fork.

It's very likely that it's a bonded aluminum fork.

Part of the assumption about the squirrel was that the squirrel was a rigid
body. As it passes between the fork legs and the spokes, the body is
contorted such that it undergoes tension and not shear forces. The body is
likely far stronger in that respect.

The squirrel is also near the rim. If it were close to the hub, the chances
of it being cut/torn/ripped rather than breaking the fork are higher.

--
Phil, Squid-in-Training

Dan said:

"Andrew Lee" <whatsupandrewathotmaildotcom> wrote in message
news:[email hidden]...

Quoted message said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his
friend on Mark's bike in last month's thread (except the bike is not
a Habanero). I wonder what that fork is aluminum or carbon?

In the earlier thread some opined that a soft squirrel was not
capable of causing this type of accident. I still think that there is
enough substance to a squirrel to stop the front wheel. These photos
look authentic enough and I would love to learn the details.

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded,
there must be a vertical force in excess of the combined rider and
bike weight. I can't tell if it is carbon or not. If it is carbon,
carbon forks often take 800 lbs or so to break when loaded at the
dropout. If the force is applied to the tire contact patch, the
moment arm is roughly doubled and it requires a force on the order of
400 lbs to break the fork (some forks may be stronger or weaker).
John Forester proposes how this might happen here:
http://www.johnforester.com/Articles/BicycleEng/forkbend.htm I have looked
at this type of failure before and tried to figure out
the dynamics. I think it can occur but is very rare. I am not sure
but a ductile (e.g steel) fork may perform better in this scenario
than a more brittle (e.g carbon fiber) fork.

Oh, and long live 32+ spoke count, squirrel-free wheels!
--
Phil, Squid-in-Training

Dan said:

In the earlier thread some opined that a soft squirrel was not capable of
causing this type of accident. I still think that there is enough substance
to a squirrel to stop the front wheel. These photos look authentic enough
and I would love to learn the details.

Cripes even a thick sock could stop a wheel dead if it got wedged in the right (or more appropriately very wrong place). The spokes holding are a lot more amazing to me than the rodent being strong enough!!

Dan said:

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded, there must be
a vertical force in excess of the combined rider and bike weight. I can't
tell if it is carbon or not. If it is carbon, carbon forks often take 800
lbs or so to break when loaded at the dropout. If the force is applied to
the tire contact patch, the moment arm is roughly doubled and it requires a
force on the order of 400 lbs to break the fork (some forks may be stronger
or weaker). John Forester proposes how this might happen here:
http://www.johnforester.com/Articles/BicycleEng/forkbend.htm
I have looked at this type of failure before and tried to figure out the
dynamics. I think it can occur but is very rare. I am not sure but a ductile
(e.g steel) fork may perform better in this scenario than a more brittle
(e.g carbon fiber) fork.

Oddly enough, to me it looks like the fork may have failed under tension at the bond between the fork arms and the fork crown (possibly CF epoxied into an alloy crown? )from the way the little critter rotated into it.

It's times like this that I can't help but wonder if a Spinergy wheel
wouldn't have resulted in a better (if more gory) outcome...

- -
These comments compliments of,
Your Friendly Neighborhood Wheelman

My web Site:
http://geocities.com/czcorner

To E-mail me:
ChrisZCorner "at" webtv "dot" net

Andrew Lee' whatsupandrewathotmaildotcom said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

If it was, I swear I'd move somewhere where there are no squirrels.
Hey wait.. I already did! ;-)

Quoted message said:

I wonder what that fork is aluminum or carbon?

It appears to be aluminum (seems like it "tore" rather than "broke"😉.
Perhaps Mike J could fill us in (being the guru of all things Trek).

I appreciate you posting that link - there were those who doubted the
veracity of me and/or my buddy when I/he said that a large squirrel
broke both legs on his Kestrel EMS fork.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Mark Hickey said:

I appreciate you posting that link - there were those who doubted the
veracity of me and/or my buddy when I/he said that a large squirrel
broke both legs on his Kestrel EMS fork.

You're welcome. I was debating whether or not to bring up the subject
again, but I did remember people doubting you on that...

Andrew

It did not for Dan Leikvold
http://www.spfldcycling.org/QR/dec04-jan05.pdf
He was using spinergy wheels when a squirrel ran into his front wheel
14 months ago..
He just went back to work last month, in a wheel chair.

Chris Z The Wheelman said:

It's times like this that I can't help but wonder if a Spinergy wheel
wouldn't have resulted in a better (if more gory) outcome...

Luke said:

In article <[email hidden]>, Dan

Quoted message said:

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded, there must be
a vertical force in excess of the combined rider and bike weight. I can't
tell if it is carbon or not. If it is carbon, carbon forks often take 800
lbs or so to break when loaded at the dropout. If the force is applied to
the tire contact patch, the moment arm is roughly doubled and it requires a
force on the order of 400 lbs to break the fork (some forks may be stronger
or weaker).

<snip>

Add to your equations the impact of the recently deceased's
deliverence: a kilo(?) travelling at nearly the speed of the bike/rider

Closer to *twice* the speed of the bike and rider, if the squirrel is
near the (top of the) rim.

Quoted message said:

applied in such a way as to leverage the force exerted by
deacceleration.

Yup, this is the nastiest sort of destructive force that forks *weren't*
designed for.

Mark

"Mark Janeba" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Luke said:

In article <[email hidden]>, Dan

Quoted message said:

For me, the really cool thing in these pictures is the broken fork.
Since the tire will skid when the friction coefficient is exceeded, there
must be a vertical force in excess of the combined rider and bike weight.
I can't tell if it is carbon or not. If it is carbon, carbon forks often
take 800 lbs or so to break when loaded at the dropout. If the force is
applied to the tire contact patch, the moment arm is roughly doubled and
it requires a force on the order of 400 lbs to break the fork (some forks
may be stronger or weaker).

<snip>

Add to your equations the impact of the recently deceased's
deliverence: a kilo(?) travelling at nearly the speed of the bike/rider

Closer to *twice* the speed of the bike and rider, if the squirrel is near
the (top of the) rim.

Quoted message said:

applied in such a way as to leverage the force exerted by
deacceleration.

Yup, this is the nastiest sort of destructive force that forks *weren't*
designed for.

An aero fork totally would have taken care of that squirrel 😉

--
Phil, Squid-in-Training

Mark Janeba said:

Luke wrote:

Quoted message said:

Quoted message said:

Add to your equations the impact of the recently deceased's
deliverence: a kilo(?) travelling at nearly the speed of the bike/rider

Closer to *twice* the speed of the bike and rider, if the squirrel is
near the (top of the) rim.

But the squirrel is only moving a bit less than the forward speed of
the bike relative to the fork (which is what matters).

Quoted message said:

Quoted message said:

applied in such a way as to leverage the force exerted by
deacceleration.

Yup, this is the nastiest sort of destructive force that forks *weren't*
designed for.

Exactly - when you think about it, it's pretty much the "perfect
storm" when it comes to destructive forces you can apply to a fork
(full-on decelleration, with a "karate chop" to the back of the fork
below the crown in the opposite direction).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Phil said:

"Mark Janeba" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Luke said:

In article <[email hidden]>, Dan
<[email hidden]> wrote:

>For me, the really cool thing in these pictures is the broken fork.
>Since the tire will skid when the friction coefficient is exceeded, there
>must be a vertical force in excess of the combined rider and bike weight.
>I can't tell if it is carbon or not. If it is carbon, carbon forks often
>take 800 lbs or so to break when loaded at the dropout. If the force is
>applied to the tire contact patch, the moment arm is roughly doubled and
>it requires a force on the order of 400 lbs to break the fork (some forks
>may be stronger or weaker).

<snip>

Add to your equations the impact of the recently deceased's
deliverence: a kilo(?) travelling at nearly the speed of the bike/rider

Closer to *twice* the speed of the bike and rider, if the squirrel is near
the (top of the) rim.

Quoted message said:

applied in such a way as to leverage the force exerted by
deacceleration.

Yup, this is the nastiest sort of destructive force that forks *weren't*
designed for.

An aero fork totally would have taken care of that squirrel 😉

Hah! Finally a use for the old Schwinn Varsity flatbladed forks - you
could sharpen their trailing edges and never worry about squirrel
destruction again!

Mark

Mark Hickey said:

Mark Janeba said:

Luke wrote:

Quoted message said:

Quoted message said:

Add to your equations the impact of the recently deceased's
deliverence: a kilo(?) travelling at nearly the speed of the bike/rider

Closer to *twice* the speed of the bike and rider, if the squirrel is
near the (top of the) rim.

But the squirrel is only moving a bit less than the forward speed of
the bike relative to the fork (which is what matters).

Oops - quite right.

Mark

On Sat, 17 Dec 2005 13:31:59 -0900, "Andrew Lee"

whatsupandrewathotmaildotcom said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

Given that one photo makes it pretty clear that the left leg went
S-shaped and stayed that way, I'd have to say that carbon is ruled
out. The Trek 1000 is, according to their website, equipped with a
carbon fork for 2005 and 2006, but had a light-alloy fork in 2003 and
2004...however it did not have the paired-spoke rims in 2004 and
prior, so the equipment is a mismatch if I'm reading the photo
evidence correctly.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Werehatrack said:

On Sat, 17 Dec 2005 13:31:59 -0900, "Andrew Lee"

whatsupandrewathotmaildotcom said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

Given that one photo makes it pretty clear that the left leg went
S-shaped and stayed that way, I'd have to say that carbon is ruled
out. The Trek 1000 is, according to their website, equipped with a
carbon fork for 2005 and 2006, but had a light-alloy fork in 2003 and
2004...however it did not have the paired-spoke rims in 2004 and
prior, so the equipment is a mismatch if I'm reading the photo
evidence correctly.

And on further consideration, I begin to wonder if this isn't yet
another (admittedly tenuous) reason to avoid the low-count
paired-spoke wheels, since the space between each of the 36 spokes on
a more conventional wheel should presumably act to prevent the
squirrel from having such an easy time getting itself into this
predicament...
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Dan said:

"Andrew Lee" <whatsupandrewathotmaildotcom> wrote in message
news:[email hidden]...

Quoted message said:

http://www.bikeforums.net/showthread.php?t=160488

It looks a lot like what Mark Hickey described happened to his friend on
Mark's bike in last month's thread (except the bike is not a Habanero).

I wonder what that fork is aluminum or carbon?

In the earlier thread some opined that a soft squirrel was not capable of
causing this type of accident. I still think that there is enough substance
to a squirrel to stop the front wheel. These photos look authentic enough
and I would love to learn the details.

For me, the really cool thing in these pictures is the broken fork. Since
the tire will skid when the friction coefficient is exceeded, there must be
a vertical force in excess of the combined rider and bike weight. I can't
tell if it is carbon or not. If it is carbon, carbon forks often take 800
lbs or so to break when loaded at the dropout. If the force is applied to
the tire contact patch, the moment arm is roughly doubled and it requires a
force on the order of 400 lbs to break the fork (some forks may be stronger
or weaker). John Forester proposes how this might happen here:
http://www.johnforester.com/Articles/BicycleEng/forkbend.htm
I have looked at this type of failure before and tried to figure out the
dynamics. I think it can occur but is very rare. I am not sure but a ductile
(e.g steel) fork may perform better in this scenario than a more brittle
(e.g carbon fiber) fork.

Check me here
Centrifugal force flings squirrel to the rim and as he goes limp, beyond the rim
on either side. Carcass wedges between the tire and side of the rim and the
crown of the fork. That would cause a jam far more severe than something as soft
as a dead or dying squirrel being caught between spoke and fork blade.

Ron

ran into a squirrel yesterday. was holding a nut he was and headed
toward the trees when i hove too and lo! if the criiter didn't stop
turn around and run straight under the front
and expletiuve deleted stop there: amazing